Nigella Lawson faced questions on drug-taking in the trial of former personal assistants (AFP/Getty) AFP/Getty

Victims and witnesses will be warned if they are likely to face detailed cross-examination about their private lives to prevent them being “ambushed” by the defence during criminal trials, under new plans unveiled today.

The plans follow the “vilification” of Nigella Lawson, who was questioned in detail about drug-taking during the trial of two former personal assistants accused of defrauding the television chef and her ex-husband Charles Saatchi.

In another case, the father of Milly Dowler, the teenager murdered by wheel clamper Levi Bellfield in 2002, was subjected to a brutal cross-examination by the killer’s lawyer about pornography found at his home. Legal experts had warned that witnesses could be unwilling to perform their public duty if they or their families were exposed to public ridicule.

The new proposals by Alison Saunders, the Director of Public Prosecutions, do not end ferocious cross-examination but aim to better prepare witnesses to face it.